<dx-tree-view
  height="90%"
  [items]="treeItems"
  selectionMode='single'
  [expandAllEnabled]='true'
  dataStructure="plain" 
  keyExpr="id" 
  displayExpr="text" 
  parentIdExpr="parentId" 
  hasItemsExpr="isGroup"
  loadMode="raw"
  noDataText="暂无数据" 
  virtualModeEnabled="true"
  [selectByClick]='true'
  (onItemClick)="changeSelection($event)"
>
</dx-tree-view>